Update yt_dlp/extractor/facebook.py

Co-authored-by: sepro <4618135+seproDev@users.noreply.github.com>

yt_dlp/extractor/facebook.py

@@ -423,18 +423,18 @@ class FacebookIE(InfoExtractor):
             snippet = traverse_obj(post, (..., 'video', ..., 'attachments', ..., lambda k, v: (
                 k == 'media' and str(v['id']) == video_id and v['__typename'] == 'Video')), expected_type=dict) or {}
             locale = self._html_search_meta(['og:locale', 'twitter:locale'], webpage, 'locale', default='en_US')
-            captions = get_first(snippet, ('video_available_captions_locales')) or get_first(snippet, ('captions_url')) or None
+            captions = get_first(snippet, 'video_available_captions_locales', 'captions_url')
             useIsVideoBroadcast = get_first(snippet, ('is_video_broadcast')) or False
             automatic_captions = {}
             subtitles = {}
             if isinstance(captions, str):
-                subtitles[locale] = [{'ext': self._search_regex(r'\.(\w{3,})\?', captions, 'captions_ext', default='srt'), 'url': captions}]
+                subtitles[locale] = [{'ext': determine_ext(captions, default_ext='srt'), 'url': captions}]
             elif isinstance(captions, list):
                 if len(captions) > 1:
                     captions = sorted(captions, key=lambda c: (c['locale'] != locale, c['locale']))
                 for c in captions:
                     s = {
-                        'ext': self._search_regex(r'\.(\w{3,})\?', c['captions_url'], 'captions_ext', default='srt'),
+                        'ext': determine_ext(c['captions_url'], default_ext='srt'),
                         'url': c['captions_url'],
                         'name': (c['localized_language']
                                  + (' (' + c['localized_country'] + ')' if c['localized_country'] else '')